engr; I am would start by setting up a timer in the PLC that resets itself about every 10 seconds or how ever often you need the efficiency calc updated, maybe every 60 seconds. When this timer finished I would have it toggle a bit that would calculate your efficiency. This should let the display keep up. You do not want to do it to often or you will bog down the PLC with coms to the HMI with passing data. If you are using ProTool Pro you can do a Script to do the calc in the HMI. I do not know anything about WinCC, but I figure you can do the same with it. Just setup your script to run every time the above mentioned bit is toggled. If you need more help just PM me and I will try and see If I can help. Larry
